llvm-project/libclc/ptx-nvidiacl/include/clc/workitem/get_num_groups.h

_CLC_INLINE size_t get_num_groups(uint dim) {
  switch (dim) {
  case 0:  return __builtin_ptx_read_nctaid_x();
  case 1:  return __builtin_ptx_read_nctaid_y();
  case 2:  return __builtin_ptx_read_nctaid_z();
  default: return 0;
  }
}